Electromotive Linear Drive

ABSTRACT

The invention relates to an electromotive linear drive ( 10 ) for adjustable components of furniture. The electromotive linear drive is constructed in such a manner that the full function is guaranteed, for the smallest possible dimensions and for the smallest possible number of components. According to the invention, the output element of the rotation speed reduction gear ( 27, 28 ), is a toothed wheel or worm wheel ( 28 ) provided with a centrically inner threaded bore. The actuator is an adjusting spindle ( 29 ) which is in contact with the toothed wheel or the worm wheel ( 28 ) and prevented form rotating and can only move in the spindle&#39;s longitudinal direction. The housing ( 11 ) has recesses which are covered by a closing element ( 16 ), with an axis of the furniture arranged in the recesses. The inventive electromotive linear drive ( 10 ) is particularly suitable for the adjustable elements of a slatted frame.

BACKGROUND OF THE INVENTION

The invention is directed to an electromotive linear drive for the adjustable components of an item of furniture, with a housing having spaced-apart housing walls with aligned openings for receiving the axle of a movable furniture component, and with a closing element which covers the openings and is secured on the corresponding edges of the housing walls for securing the axle, with a drive motor and a rotation speed reduction gear coupled to the drive motor and having at least one driven element for driving at least one linearly movable actuator which operates on an articulated lever attached to the axle for converting its linear motion into a rotary motion of the axle.

The aforedescribed electromotive linear drive is known in many variations. It represents a so-called single drive with a drive motor and an actuator. The electromotive linear drive can be used to adjust the stationery, but rotatably supported shaft of the backrest or the foot section of a slatted frame. These are mass-produced articles which should be offered that the lowest possible price. As many components as possible are therefore made of plastic by injection molding. Because the rotation speed reduction gear is typically a worm gear, the worm is made of steel or the driven shaft of the drive motor is implemented as a worm. The worm wheel engaging with the worm is made of plastic. The housing is typically also a plastic housing. In conventional linear drives, the worm wheel drives a spindle which is usually also fabricated of steel, because such spindles are commercially available as standard parts. A spindle nut, which is secured against rotation, is placed on the spindle and moves in the longitudinal direction of the spindle, when the spindle rotates, depending on the rotation direction. The spindle nut is made of plastic and presses against the articulated lever made of steel. The end positions of the spindle nut are typically preset by two limit switches. Such drives should be quite compact when used in conjunction with a slatted frame, because the manufacturer of a slatted frame already installs these linear drives on the slatted frame. Moreover, the height of a slatted frame should also be as small as possible to facilitate stacking, and provide space-saving storage and space-saving transport.

In conventional implementations with a spindle and an attached spindle nut, the linear drive is relatively long, whereby the length of the linear drive is defined as the distance between one end and the opposite end, wherein the contemplated connection extends transversely to the rotary shaft of the motor.

SUMMARY OF THE INVENTION

It is an object of the invention to design an electromotive linear drive of the aforedescribed type, so that full functionality is ensured with the smallest possible dimensions and the smallest possible number of components.

The object is solved in that the driven element of the rotation speed reduction gear is a toothed wheel or a worm wheel, which is provided with a central bore having an interior thread, and that the actuator is an adjusting spindle which is in engagement with the toothed wheel or a worm wheel and secured against rotation and only moveable along its longitudinal direction, wherein the adjusting spindle is operatively connected with the articulated lever.

Unlike with conventional embodiments, the toothed wheel or worm wheel of the rotation speed reduction gear is hereby provided with a central bore with an interior thread, which engages with the spindle forming the actuator. When the toothed wheel or worm wheel turns, the spindle moves relative to the toothed wheel or worm wheel in a direction that depends on the rotation direction of the toothed wheel or worm wheel. Because the actuating spindle is directly or indirectly operatively connected with the articulated lever, not only is the spindle nut eliminated, but the length of the housing is significantly reduced compared to conventional embodiments, because unlike with conventional embodiments, the actuating spindle is now located on both sides of the toothed wheel or worm wheel. The reduced dimensions of the housing also save material, thereby lowering the total manufacturing costs. The travel speed of the connected furniture component is not decreased, because the pitch of the threaded portion of the actuating spindle can be designed so that the spindle nut attains the same speed as with conventional drives.

According to another embodiment, the closing element is moveable in the longitudinal direction of the axle in guides of the housing walls and is formfittingly connected in the end position with the upper edges of the housing walls.

The closing element now moves transversely to the longitudinal axis of the housing, so that force transmission is more advantageous than with the conventional linear drives. In the aforedescribed linear drives, the forces act in the longitudinal direction of the housing due to the configuration of the drive arrangement and therefore transverse to the travel direction of the closing element. The closing element in conventional linear drives is always viewed as a critical element of the drive. In the linear drive of the invention, the forces applied to the closing element can be transferred via the contact faces between the closing element and the housing walls.

A formfitting connection between the closing element and the housing walls is achieved by providing at least two undercut grooves in each housing wall, whereby the undercut grooves in the housing walls are aligned with one another. These components are made of plastic and can be shaped by a suitable design of the injection mold or injection molds. To achieve adequate guiding and an acceptable surface pressure, two grooves are provided in each housing wall on both sides of the aligned recesses, wherein at least the groove facing the recess is undercut. The closing element has, for formfitting attachment, safety ribs which engage with grooves disposed in the housing walls. These safety ribs extend advantageously from one longitudinal side to the opposite longitudinal side, which facilitates insertion of the closing element from the side. The closing element can also be provided with safety elements along its outside edges which prevent accidental movement of the closing element. These safety elements may include integrally formed ribs, beads, components which are additionally joined with the closing element, or a combination of thereof, which extend for force transmission or formfittingly behind a housing edge or in a housing edge, after the closing element is placed in its final position. Advantageously, the closing element is stabilized by longitudinal ribs extending on the free outer surface in the longitudinal direction; the ribs may also may extent through the outside towards the inside. Because the closing element is mainly subjected to a bending load, longitudinal or transverse ribs of significant height are advantageous, which may extent over the entire height of the closing element. To prevent accidental movement of the closing element, the closing element may include integrally formed or attached sections which engage for force transmission and/or formfittingly in the housing or on the housing. In addition, the safety elements can also be housed inside the housing. Advantageously, the safety element may be held between the housing parts after the linear drive is installed, while a free end of the safety element engages springily with or snaps into a recess of the closing element, thereby securing the closing element against accidental movement.

The housing of the aforedescribed electromotive linear drive is conventionally fabricated of plastic and is made of two housing halves, with the contacting surfaces arranged transversely to the rotary shaft of the motor. This facilitates installation of the components arranged in the interior, because the housing halves are then oriented in the installation position so as to be open towards the top, thereby leaving adequate space for assembly robots. The components arranged inside the housing halves are preferably secured without mechanical connecting elements simply by a corresponding shape of the housing halves, thereby eliminating mechanical connecting elements. Because the generated forces are transferred via the housing halves, the contacting surfaces of the housing halves are profiled, toothed or have a similar shape, and mesh with one another. Alternatively, the screw domes can include ring-shaped pegs, ribs or recesses which are arranged repeatedly and concentrically about the mounting screws. Alternatively, the housing halves may include ring-shaped pegs, ribs or openings which are arranged concentrically with respect to one another and extend around fastening screws such that the housing halves nest with each other when the screws are tightened. When the two housing halves are mounted, these pegs, ribs or recesses engage with one another and are firmly pressed into each other when the respective screw is tightened, so that the housing halves are secured against each other formfittingly and immovably. This effectively prevents even a small displacement of the two housing halves relative to one another. To keep the wall thickness of the housing halves as small as possible, the wall thickness can be reduced through reinforcement with fibers, preferably glass fibers.

The electromotive linear drive can operate by having the spindle extend or protrude from the housing when the spindle is retracted, i.e., when the connected furniture component is lowered. However, the spindle would then be exposed to the environment, for example to contamination from dust. To this end, the housing includes a cover made of a rigid or elastic material and located on the side facing away from the articulated lever, with the spindle engaging with the cover in the retracted position. The cover may be snapped onto the housing or screwed together with the housing; advantageously, the housing together with the cover may be formed as a single molded piece. To prevent the housing or the electromotive linear drive from rotating when the drive motor that adjusts the connected furniture component is energized, the housing may include an opening or a recess on the side facing the drive motor for providing a torque support. Advantageously, the width of the opening of the torque support may be adjusted by a component or a closing mechanism, or the opening may be covered with an additional closing element. The cross-sectional shape of this opening or recess is adapted to the component, and is preferably either circular or semicircular. With the open design, the linear drive can advantageously be attached to the component forming the support.

To give the housing sufficient rigidity for force transmission, the housing may include intersecting reinforcing ribs. To give the housing an appealing shape, since it is preferably smooth on the outside, with the intersecting reinforcing ribs arranged in the interior of the housing.

At least the ribs adjacent to the recesses can be concentric with the recesses. The intersecting ribs or the ribs oriented towards the recesses extend initially parallel and are spaced from the upper edge of the housing, and thereafter at an acute angle. To prevent obstruction of the travel of the articulated lever that lifts the furniture component, reinforcing ribs are absent from the travel area. Advantageously, the outer wall of the housing may jut outward in the immediate vicinity of this housing region, may have an outward curvature, or may have a combination of these features. Accordingly, the ribbed structure on the interior side of the housing can be even more prominent, whereby the housing can be designed to be stiff in zones exposed to high loads.

Depending on the application of the electromotive linear drive, the spindle can be made of steel or plastic. If the spindle is made of plastic, a pressure block is fixedly placed on the end region of the spindle facing the articulated lever to prevent the end region from deforming. The pressure block is advantageously made of plastic, preferably forms a molded part together with the spindle, and is provided with a metallic reinforcing insert. The metallic reinforcing insert may be located inside the block, whereby the metallic reinforcing element can be manufactured by extrusion-coating. However, the metallic reinforcing insert can also be attached to the plastic block of the side facing the articulated lever or snapped together with the plastic block if the plastic block is suitably shaped. The metallic reinforcing insert can also be constructed as a clip. If the spindle is made of steel, a pressure block made of steel or plastic can be connected with the spindle formfittingly or by a material connection. The contact surface between the pressure block and the articulated lever can also be oriented at a right angle with respect to the longitudinal center axis of the spindle or can be inclined with a relatively small acute angle, whereby this angle can be for example between 5° and 20°. The articulated lever is typically made of steel. This combination of materials is generally disadvantageous, but may be practical in the present example, because the travel speed of the spindle is relatively low. The pressure block or the reinforcing insert can also be made, at least in certain sections, of hardened steel, which minimizes wear between this component and the articulated lever. At least the surface of the articulated lever may also be hardened in the region contacting the pressure block or the reinforcing insert. Moreover, another material potentially harder than steel could be used in lieu of the pressure block or the reinforcing insert made of steel, for example, hard metal alloys or ceramics.

In a preferred embodiment, the articulated lever made of metal has an angular shape and can be fabricated as a punched part of steel or as a cast steel part with parallel side faces. The material combination where steel frictionally engages with steel can produce disconcerting noise which can be eliminated by shaping the surface of the articulated lever facing the pressure block as an arc or as a semicircle. For keeping the parts count as low as possible, it is generally known to have an arcuate section of the articulated lever directly contact the driven element of the linear drive along a line, and to have the arcuate section of the articulated lever frictionally engage with the end phase of the linearly movable driven element. This line contact produces high contact forces, which may cause excessive wear. In another embodiment, a pressure plate similar to a sliding block is arranged between the arcuate section of the articulated lever and the friction surface of the linear driven element. The pressure plate has on the side facing the articulated lever a circular trough which cooperates with a circular arcuate section of the articulated lever. During operation of the linear drive, the arcuate section of the articulated lever frictionally engages with the trough in the pressure plate, and the flat surface of the pressure plate frictionally engages with the linear driven element in front of the contact surface. This additional component transforms the aforedescribed linear contact into an area contact, distributing the forces over a significantly larger area.

To simplify the installation of the electromotive linear drive, for example in an article furniture, it may be advantageous to secure the pressure plate on ribs disposed on the linear driven element. Alternatively, the pressure plate may also be connected to or firmly attached to the articulated lever, thereby providing a kind of articulated joint between the articulated lever and the pressure plate, for example through trough-shaped recesses.

The worm wheel is advantageously supported by a roller bearing which is inserted in a gear angle implemented as a molded or cast part and connected by screws with the housing of the drive motor. The gear angle is made of a sleeve and a mounting flange attached to the sleeve. The gear angle can be easily manufactured as a molded plastic part and can be reinforced with fibers, preferably glass fibers.

To optimize the frictionally engaging parts, on one hand, between the motor shaft and the worm gear and, on the other hand, between the worm gear and the spindle, the worm wheel is formed in two parts and includes an outer rim and a support sleeve engaging with the outer rim, wherein the support sleeve is provided with the interior thread and on the outside with a bearing seat for the roller bearing. The components are made of different materials, which in particular make it possible to use only a single roller bearing for supporting the worm gear and the spindle. Advantageously, the outer rim is formfittingly connected with the support sleeve, for example, through ribs engaging with grooves formed in the other component. Alternatively, the worm wheel with the interior thread and the outer bearing seat for the roller bearing may also be formed as a one-piece molded plastic part. This reduces the overall number of components.

Preferably, the aforedescribed linear drives are preferably self-locking through suitable design of the spindle and, in the present example, also the interior thread, meaning that the connected component remains in the respective position when the drive motor is switched off. However, an increase in the travel speed requires spindles with a greater pitch, so that the linear drives are no longer self-locking. According to another embodiment, the linear drive may include a brake element acting in a travel direction of the spindle which is mounted between a rotating component and a stationary component. In a preferred embodiment, this component is a spring brake element having several turns, whereby one end of the winding is secured in the sleeve of the gear angle, while the spring brake element is otherwise arranged on the bearing seat of the worm wheel. Alternatively, the free windings of the spring brake element may be wound around a cylindrical projection.

In an embodiment employing a spindle made of steel, the end of the spindle facing away from the drive motor, instead of the pressure block, could operate on a slide block which is movably guided in the housing and which operates on the articulated lever. In one embodiment, the sliding block could be made of plastic, so that the material combination between the movable articulated lever and the sliding block would match. The end face of the spindle could be oriented perpendicular to the longitudinal center axis of the spindle or at an angle, for example with respect to the vertical, which would optimize force transmission to the articulated lever. Because it is desirable to install the aforedescribed linear drives with assembly robots, which requires keeping the number of mechanical mounting elements as small as possible, the housing halves include mounting ribs oriented transversely to the longitudinal center axis of the spindle and supporting the end faces of the sleeve of the gear angle. When the electromotive linear drive adjusts the furniture component against gravity, this occurs in the major loading direction. The item of furniture can be returned to its original position by gravity, whereby the aforementioned stop edge may support the gear or a gear component against displacement. A pressure element of the spindle operating on the articulated lever may be designed to have steps, with the stepped surface located on the side facing the articulated lever, thereby providing an area contact between the side surface of the articulated lever and the stepped surface.

The housing is advantageously designed so that the drive motor with the flanged-on gear angle and the worm wheel as well as the roller bearing can be mounted in the housing as a unit, and that the contact surfaces with the housing or with the housing half can provide support without the use of mechanical elements, for example safety elements. The aforedescribed electromotive linear drive is preferably used to adjust furniture components. As little noise as possible, which also should not be objectionable, should be emitted with the linear drive switched on. For this reason, at least the region located between the gear angle and the housing is filled with a sound-absorbing material. This could be, for example, an inserted rubber element or an extrusion-cast resilient element disposed on the housing and/or the gear. In cross-section, the housing is rounded at least on the bottom side facing the openings for the axle. To facilitate stacking of those slatted frames during transport, which are already provided with one of several electromotive linear drives, two transport elements can be attached to the housing formfittingly and/or for force transmission. This prevents the slatted frames from tipping or sliding relative to one another. Advantageously, the free side of the transport elements, i.e. the side facing away from the housing, includes aligned semicircular tapers. However, these tapers can also be integrally formed on the housing halves of the electromotive linear drive.

A terminal for a power cable can be provided on the housing near the drive motor for supplying electric power to the drive motor. A printed circuit board can be arranged inside the housing or in a extended space of the housing, so that cables can be eliminated. Advantageously, the motor including the terminal are protected by a cover, which prevents interruption of the electric power. These items are particularly difficult to repair, because the electromotive linear drives of articles furniture are typically not easily accessible. Finally, the end positions of the spindle are limited by limit switches.

The pressure block can also be made of steel and welded with a steel spindle. To prevent abrasion caused by movement of the pressure block, the steel pressure block may be provided with an externally applied plastic guide, which in a preferred embodiment has two plastic caps which are, for example, placed on the sides of the pressure block, preferably formfittingly. The caps can also be screwed together.

Moreover, a control board with mounted electric components for controlling at least one electric motor can be arranged inside the housing, or a printed circuit board could be installed inside the housing as a current distribution board to separate and forward the electric signals to the control and the power supply.

In addition, ribs, pegs or rails may be formed on the housing for formfitting attachment of a control housing or a power distribution unit. The housing may include additional ribs and/or recesses for formfitting attachment of a power cable or a power distribution or a plug connector for transmitting electric power.

These as well as additional ribs or pegs can also be used for attaching power supply units, control units and mounting units, so that for example all devices, equipment, operating components and mounting means required for the operation may be attached to the housing during transport of the electromotive linear drive, thereby forming a compact unit. These include, for example, transformers, DC power supplies, manual switches of the closing elements, etc. To this end, suitably shaped pockets or ribs for receiving these components are provided on the housing. The elements or components attached to the housing can be detached from the housing after transport

Moreover, ribs may be formed on or integrated in the housing for securing a connecting cable. Radii or arcuate sections or molded sections are also provided for supporting a cable so as not to a low a bending radius smaller than a minimally allowable bending radius. To this end, ribs or pegs are formed on the housing or in the housing to secure a cable for stress relief. Arcuate projections or recesses may also be formed on the housing or in the housing for supporting a cable with a minimum allowable bending radius as an anti-kink protection for the cable.

In addition, the motor connection can be designed as a plug connection. To prevent the plug from being pulled out accidentally, ribs can be formed on the housing of the linear drive which hold the housing of the plug in force transmitting or formfitting engagement. Instead or in addition, safety elements can also be attached on the housing of the being a drive, which secure the plug or the cable leading from the plug on the housing of the linear drive. This can be implemented by forming ribs or pegs on the housing or in the housing, which connect at least one terminal, for example a motor terminal, with the housing for force transmission or formfittingly. Alternatively, a safety element which secures a motor terminal on the housing may be attached to the pegs or ribs.

According to another embodiment, the linear drive and the housing may be constructed so that the drive can be installed, for example in an article furniture, without tools and by simple manipulation or by a robot. The linear drive and the housing are constructed to allow installation by hand or by a machine without the use of tools.

Use of the linear drive is normally limited to dry environments. To expand the applications of the linear drive, a seal is provided to prevent moisture and dust from entering the drive. The contacting surfaces of the housing can be implemented as a labyrinth seal. Preferably, one or several sealing elements made, for example, of an elastic material are introduced between the contacting surfaces of the housing parts, between the contacting surfaces located between the closing element, the housing and the axle. For example, one or several sealing elements for sealing the linear drive can be provided between the housing parts, the cover, the closing element, the axle, and the motor connection. The sealing elements can be implemented as individual and elastic elements or can be integrally formed on the components of the linear drive.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows an electromotive linear drive according to the invention in a perspective view, viewed toward the side facing away from the drive motor;

FIG. 2 shows the electromotive linear drive of FIG. 1, viewed toward the side facing the drive motor;

FIG. 3 is a cross-sectional view corresponding to FIG. 1;

FIG. 4 shows a diagram corresponding to that of FIG. 1, however with a power/signal distribution panel attached to the housing; and

FIG. 5 shows a diagram corresponding to that of FIG. 2, however with a control housing attached to the housing.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The electromotive linear drive illustrated in FIGS. 1 to 5 is a so-called single drive, i.e., the drive is designed to adjust a furniture component, in particular the backrest or the footrest of a slatted frame. The gear components of the electromotive linear drive 10 are arranged in a generally closed housing 11, which is composed of two housing halves 11 a and 11 b. The gear components are driven by a conventional DC motor which also has an outer housing 11. The housing 11 and the housing halves 11 a and 11 b are made of plastic. The two housing halves 11 a and 11 b are connected with several screws 13 which are screwed into domes of the housings half 11 b in a manner not described in detail. The domes are formfittingly connected with corresponding counter elements in the other housing half 11 a, thereby effectively preventing displacement between the housing halves 11 a and 11 b under load.

As will be described in more detail with reference to FIG. 3, an articulated lever 15 is non-rotatably positioned on an axle 14, for example the axle of a slatted frame. The electromotive linear drive 10 is secured on the axle 14 by a plate-shaped closing element 16. Four ribs 17, 18, 19, and 20 which engage with corresponding grooves are located on the side of the closing element 16 facing the two housing halves 11 a and 11 b. The ribs 17 to 20 are parallel to and spaced from the axle 14, so that the closing element 16 can be pushed onto the housing halves 11 a and 11 b from the side. The closing element 16 can therefore support a high load because the major load direction is oriented transversely to the axle 14. The ribs 18, 19 facing the axle 14 are in the illustrated embodiments provided with sloped surfaces, thereby producing a formfitting engagement with the correspondingly formed grooves of the housing halves 11 a and 11 b.

As will be described with reference to FIG. 3, the drive member of the electromotive linear drive 10 is a spindle 21 which travels in the longitudinal direction. A cover 11 c, which in a preferred embodiment is formed as one piece with the housing halves 11 a and 11 b, is attached to the housing to protect the spindle 21 when the connected furniture component is in the lowered position. It should also be mentioned that the contacting surfaces of the two housing halves 11 a and 11 b extend perpendicular to the axle 14, i.e., the contacting faces are vertical in the mounting position. The electromotive linear drive 10 requires an additional support for its operation. To this end, the housing includes not only U-shaped recesses for receiving the axle 14, but also includes a torque support located on the opposite side which in the illustrated embodiments is formed by semicircular rings 22, allowing the electromotive linear drive 10 to be suspended from an article of furniture. The electromotive linear drive 10 is typically installed in the furniture item, for example on the slatted frame, by the furniture manufacturer. Because slatted frames are, for example, stored and transported stacked, the electromotive linear drive 10 includes of the side facing away from the axle 14 transported elements 23, which have semicircular recesses on the side facing away from the housing 11, but are otherwise attached to the housing.

As shown in FIG. 2, the side of the housing 11 facing the region 12 of the housing of the drive motor is provided with an electric power distribution panel 24, which is detachable and/or attached or snapped on, as shown in FIG. 4. In this exemplary embodiment, the power distribution panel 24 includes four terminals 25, with one terminal being used for connection with the power mains, another terminal for connection with another electromotive linear drive, one terminal for the motor connection 26, and another terminal for connection with a manual switch.

As shown in FIG. 3, the drive motor 12 drives a rotation speed reduction gear 31, which according to FIG. 3 is formed of a worm 27 and a worm wheel 28 engaging with the worm 27. The worm wheel 28 has a threaded interior center bore, allowing a spindle 29 engaging with the bore to travel in the longitudinal direction of the spindle. The spindle 29 is secured against rotation and supports a pressure block 30 on the side facing the articulated lever 15. The pressure block 30 can be made of steel or plastic. If the pressure block is made of plastic, it can be provided with metallic reinforcing inserts which can be extrusion-coated during manufacture and engage as a friction element with the articulated lever 15. The spindle 29 could also be made of plastic or steel. If the pressure block 30 is made of steel, it has externally applied plastic caps for reducing friction with the housing halves 11 a and 11 b. The pressure block 30 is guided through the correspondingly constructed housing 11. The pressure block 30 has steps on the side facing the articulated lever 15, with the articulated lever 15 contacting the stepped surface. The worm wheel 27 is supported by a machined part referred to as gear angle. As clearly shown in FIG. 3, the interior of the housing halves 11 a and 11 b includes ribs, whereby however the travel area of the articulated lever 15 is free from ribs. The ribs are arranged concentric to the opening in the region of the axle 14 and are additionally reinforced by intersecting ribs.

FIG. 4 shows, unlike FIG. 2, that the power distribution panel 24 can be attached to the housing 11 by way of snap-in grooves 32 provided on the housing. The power distribution panel 24 is provided with a plug connection and several fixed terminals. The pluggable connection leads to a manual operating console and is provided with a safety element which prevents the plug connection from being accidentally disconnected. The other terminals are fixedly connected with the current distribution panel and include connected cables (not shown), which conduct electric signals between a manual control unit, a power supply unit and the motor of drive 10 or the motors of additional drives.

In the embodiment depicted in FIG. 5, unlike in the other embodiments, the housing of the drive motor 12 has ribs extending in the longitudinal direction for attaching a control housing 33 which receives the controller. The control housing has a relatively small height, so that the outer unattached surface is lower than the closing element 16. The side of the control housing 33 facing the housing half 11 b is also provided with latching elements (not shown) which at least partially encompass or engage with the snap-in grooves 32, so as to securely attach the control housing 33 on the drive 10. The control housing 33 itself preferably includes a control circuit board with a control section and a power section. Control signals are supplied via the terminals 25, for example from a manual control console, whereas power actuators in the form of electromechanical switches form the power section and control the motor of drive 10 or additional motors of additional drives (not shown). Preferably, electric voltages with a low potential are processed inside the control housing 33, which are supplied to the terminals 25 in the control housing 33 from a power supply unit (not shown) implemented as a DC source or an AC source with integrated transformer. Alternatively, the power supply unit may also be part of the control housing 33. The terminals 25 can also be implemented as plug connections (not shown) and can be secured against accidental disconnection of the plug connection.

The outside of the housing 11 can also be provided with ribs or similar elements (not shown) for attaching a manual control unit. The manual control unit can thereby be secured during transport. In addition, pockets or webs for receiving batteries or rechargeable power sources can also be located in the housing 11 or on the housing 11 for supplying emergency power. 

1. An electromotive linear drive for an adjustable component of an item of furniture, comprising: a housing having spaced-apart housing walls with aligned openings for receiving an axle of a movable furniture component, a closing element which covers the openings and is secured on edges of the housing walls for securing the axle, a drive motor and a rotation speed reduction gear which is coupled to the drive motor and has at least one driven element implemented as a toothed wheel or a worm wheel having a central bore with an interior thread, and at least one linearly movable actuator which is implemented as an adjusting spindle in engagement with the toothed wheel or the worm wheel and secured against rotation, wherein the actuator is driven by the driven element so as to be moveable only along a longitudinal direction and operatively connected with an articulated lever attached to the axle for converting the linear motion of the actuator to a rotary motion of the axle.
 2. The electromotive linear drive of claim 1, further comprising guides disposed in the housing walls for guiding the closing element for movement in the longitudinal direction of the axle, wherein the closing element is formfittingly connected in an end position with upper edges of the housing walls.
 3. The electromotive linear drive of claim 2, wherein each housing wall has at least two undercut grooves which are aligned with one another.
 4. The electromotive linear drive of claim 2, wherein each housing wall has two respective grooves disposed on both sides of the aligned openings, and wherein at least one of the grooves facing an aligned opening is undercut.
 5. The electromotive linear drive of claim 3, wherein the closing element includes safety ribs which engage with the grooves in the housing walls.
 6. The electromotive linear drive of claim 5, wherein the safety ribs extend from one longitudinal side to an opposite longitudinal side of the closing element.
 7. The electromotive linear drive of claim 1, wherein the closing element comprises reinforcing ribs disposed on a free outer side or a free inner side of the closing element and extending in a longitudinal direction of the closing element.
 8. The electromotive linear drive of claim 1, wherein the closing element includes integrally formed or attached sections, which engage for force transmission or formfittingly in the housing or on the housing.
 9. The electromotive linear drive of claim 1, wherein the housing is made of plastic and has two housing halves with contacting surfaces, wherein the contacting surfaces of the housing halves are oriented transversely to a rotary shaft of the drive motor.
 10. The electromotive linear drive of claim 9, wherein the contacting surfaces of the housing halves are profiled, toothed or have a complementary shape, and wherein the contacting surfaces mesh with one another.
 11. The electromotive linear drive of claim 9, wherein the housing halves include ring-shaped pegs, ribs or openings which are arranged concentrically with respect to one another and extend around fastening screws such that the housing halves nest with each other when the screws are tightened.
 12. The electromotive linear drive according of claim 1, further comprising a bead forming a stop edge disposed inside of the housing for supporting the gear or a component of the gear against displacement caused by gravity during return travel of the connected furniture component.
 13. The electromotive linear drive of claim 1, wherein the housing halves are reinforced with fibers to reduce a thickness of the housing walls.
 14. The electromotive linear drive of claim 9, wherein the housing comprises a cover made of a rigid material or an elastic material and located on a side of the housing facing away from the articulated lever, with the adjusting spindle positioned in the cover in a retracted position.
 15. The electromotive linear drive of claim 14, wherein the cover is snapped onto the housing (11) or screwed together with the housing, or wherein one of the housing halves together with the cover form a single molded piece.
 16. The electromotive linear drive of claim 1, wherein the housing includes an opening or a recess on a side facing the drive motor for providing a torque support.
 17. The electromotive linear drive of claim 16, wherein a width of the opening of the torque support can be changed by way of a component or a closing mechanism, or wherein the opening can be covered by an additional closing element.
 18. The electromotive linear drive of claim 9, wherein the housing halves comprise are provided intersecting reinforcing ribs.
 19. The electromotive linear drive of claim 18, wherein the housing halves have a smooth outer surface and wherein the intersecting reinforcing ribs are arranged inside the housing halves.
 20. The electromotive linear drive of claim 18, wherein the reinforcing ribs bordering the aligned openings extend concentrically or approximately concentrically with respect to the aligned openings.
 21. The electromotive linear drive of claim 18, wherein a travel range of the articulated lever is not obstructed by reinforcing ribs.
 22. The electromotive linear drive of claim 1, wherein the spindle is made of steel or plastic.
 23. The electromotive linear drive of claim 22, further comprising a pressure block affixed on an end region of the spindle facing the articulated lever.
 24. The electromotive linear drive of claim 23, wherein the pressure block is made of plastic and comprises a metallic reinforcing insert.
 25. The electromotive linear drive of claim 23, wherein the pressure block is made of steel, and further comprising a plastic guide placed on an exterior surface of the steel pressure block, with the plastic guide comprising two plastic caps disposed on a side of the pressure block.
 26. The electromotive linear drive of claim 23, wherein the pressure block and the spindle are joined by a force-transmitting connection, a formfitting connection or a material connection, or form a molded part.
 27. The electromotive linear drive of claim 24, wherein the metallic reinforcing insert is arranged inside the plastic block or is applied to the pressure block at least on a side facing the articulated lever.
 28. The electromotive linear drive of claim 23 wherein, the pressure block, the metallic reinforcing insert of the plastic pressure block, a plate attached to a steel spindle, or an end face of the spindle itself forms the contact surface to the articulated lever, said contact surface being arranged perpendicular to the longitudinal center axis of the spindle or at an angle with an offset relative to the vertical.
 29. The electromotive linear drive of claim 1, wherein the articulated lever is angled and fabricated as a punched steel part or a cast steel part with parallel side edges.
 30. The electromotive linear drive of claim 23, wherein a surface of the articulated lever facing the pressure block is shaped as an arc or a semicircle.
 31. The electromotive linear drive of claim 1, and further comprising a roller bearing supporting the worm wheel and a gear angle implemented at a machined part.
 32. The electromotive linear drive of claim 31, wherein the gear angle includes a sleeve for receiving the roller bearing and a mounting flange for attachment to the housing of the drive motor.
 33. The electromotive linear drive of claim 24, wherein the gear angle is made of plastic and reinforced with fibers.
 34. The electromotive linear drive of claim 31, wherein, the worm wheel is formed in two parts and comprises an outer rim with a tooth pattern and a support sleeve, wherein the support sleeve is provided with the interior thread and with an outer bearing seat for the roller bearing.
 35. The electromotive linear drive to of claim 34, and further comprising ribs and grooves which formfittingly connect the outer rim with the support sleeve.
 36. The electromotive linear drive of claim 34, wherein the worm wheel together with the bearing seat and the interior thread are formed as a one-piece molded plastic part.
 37. The electromotive linear drive of claim 1, wherein the linear drive is formed as a non-self-locking drive, and wherein the linear drive further comprises a brake element effective in a travel direction of the spindle for stopping a load when the drive motor is switched off.
 38. The electromotive linear drive of claim 37, and further comprising a gear angle with a sleeve, wherein the brake element is implemented as a spring brake element having several turns and arranged in an annular gap between the sleeve and a bearing seat, with one end of a turn being secured in the sleeve of the gear angle.
 39. The electromotive linear drive of claim 1, wherein the spindle is made of steel, with a free end face facing away from the worm wheel operating on a slider element guided in the housing.
 40. The electromotive linear drive of claim 39, wherein the free end face of the spindle that faces away from the worm wheel is perpendicular to the longitudinal center axis of the spindle or is inclined with respect to the vertical and is formed as a pressure block for forming contact faces to the articulated lever.
 41. The electromotive linear drive of claim 9, wherein the housing has two housing halves with interior mounting ribs oriented transversely to the longitudinal center axis of the spindle, and further including a gear angle with a sleeve, with the mounting ribs supporting end faces of the sleeve of the gear angle.
 42. The electromotive linear drive of claim 1, further comprising a pressure element placed on the spindle, wherein the pressure element has steps on a side facing the articulated lever, thereby providing a lateral two-dimensional contact between the articulated lever and the pressure element.
 43. The electromotive linear drive of claim 31, wherein the electromotive linear drive unit with the flanged-on gear angle and the worm wheel mounted therein and the roller bearing form a mounting unit, allowing storage of the unit without use of mechanical elements.
 44. The electromotive linear drive of claim 31, wherein at least a region located between the gear angle and the housing is filled with a sound-absorbing material.
 45. The electromotive linear drive of claim 44, wherein the sound-absorbing material is formed as a rubber element, or as a rubber element that is extrusion-molded on a housing half or on the gear angle.
 46. The electromotive linear drive of claim 31, wherein a lower side of the housing, which faces away from the aligned openings, includes two transport elements adapted for attachment to the housing formfittingly or for force transmission.
 47. The electromotive linear drive of claim 46, wherein a lower side of the transport elements facing away from the housing wall includes two aligned semicircular tapers.
 48. The electromotive linear drive of claim 47, wherein the housing has two housing halves and the semicircular tapers are formed on the housing halves as a single piece.
 49. The electromotive linear drive of claim 1, wherein the housing further comprises a terminal for a power cable and a control board arranged inside the housing, such that an interior space of the housing is free from cables.
 50. The electromotive linear drive of claim 49, wherein the housing further comprises a control board arranged inside the housing or in a shaped extension of the housing with an inserted electrical component for controlling the electric motor, or a printed circuit board arranged inside the housing as a current distribution board, which separates and transmits electrical signals for control and power supply.
 51. The electromotive linear drive according of claim 1, wherein the drive motor and a terminal for supplying electric power are covered by a common cover.
 52. The electromotive linear drive of claim 1, and further comprising a limit switch for limiting an end position of the spindle.
 53. The electromotive linear drive of claim 1, wherein the housing further comprises ribs, pegs or rails for formfitting attachment of a control housing or a power distribution unit.
 54. The electromotive linear drive of claim 1, wherein the housing comprises ribs or recesses for formfitting attachment of a power cable or a power distribution or a plug connector for transmitting electric power.
 55. The electromotive linear drive of claim 1, wherein an outer surface of the housing includes ribs for attachment of a manual control unit.
 56. The electromotive linear drive of claim 1, wherein the housing includes pockets or webs for receiving batteries for supplying emergency power.
 57. The electromotive linear drive of claim 1, wherein the housing includes pockets or webs for receiving power supply units, control units and mounting units, such as transformers, DC power supplies, manual switches, and closing elements, wherein the units are detachable from the linear drive after transport.
 58. The electromotive linear drive of claim 1, wherein the housing includes ribs or pegs for securing a cable for stress relief, and arcuate projections or recesses for supporting a cable with a minimum allowable bending radius as an anti-kink protection for the cable.
 59. The electromotive linear drive according of claim 1, wherein the housing includes ribs or pegs, which connect at least one electrical terminal with the housing for force transmission or formfittingly, or a safety element attached to the pegs or ribs for securing a motor terminal on the housing.
 60. The electromotive linear drive of claim 50, wherein the at least one electrical terminal is a motor terminal.
 61. The electromotive linear drive of claim 13, wherein the fibers are glass fibers.
 62. The electromotive linear drive of claim 33, wherein the fibers are glass fibers. 